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Avian Influenza (Bird Flu)

Avian influenza (AI), commonly known as “bird flu,” is caused by an influenza type A virus.  Avian influenza viruses occur naturally in wild birds, especially waterfowl and shore or wading birds.  Wild bird species (such as ducks and geese) can carry and spread Avian Influenza viruses without becoming ill.    However,  in recent months certain types of Highly Pathogenic Avian Influenza viruses have been affecting the wild waterfowl as well as domestic poultry species. Avian influenza in birds is very contagious and can cause serious disease and high mortality in domestic poultry such as chickens, quail, pheasants, guinea fowl and turkeys. 

Current Status in Pennsylvania

On Saturday, April 16, the Pennsylvania Department of Agriculture confirmed the state's first positive case of Highly Pathogenic Avian Influenza (HPAI) in domestic poultry, in a flock of commercial layer chickens on a Lancaster County poultry farm. State and federal government, and private poultry industry representatives remain on high alert and are taking strict measures to protect Pennsylvania’s poultry industry.

Learn more: Secretary of Agriculture Provides Update on Highly Pathogenic Avian Influenza

For a complete listing of confirmed infections in the U.S. and detailed information on biosecurity visit the USDA's website here USDA APHIS | Defend the Flock Program.

Information about the current state of HPAI in Pennsylvania can be found at the HPAI Address Search Application.


Biosecurity is vital for anyone who owns or works with poultry – whether on a commercial farm, in the wild, or at a hobby/ backyard farm.  You should take proper steps to keep Avian Influenza from infecting your flock or spreading to other flocks. The best way to protect your birds is to follow good biosecurity.  Having a biosecurity plan in place, and following that plan daily, is vital to protect Pennsylvania’s poultry.  

If  you don’t already have your premises registered with the Department, please do so, and include current contact information.  If you already have your premises registered with us, please make sure we have current contact information so we can reach you.  Premise ID allows us to find your premises on a map in the event of a disease outbreak, and we can warn you if your flock is at risk due to a nearby infected flock.  

Reporting Requirements

If you suspect your poultry is infected with avian influenza, please report your concerns 24 hours a day, 7 days a week to the Pennsylvania Bureau of Animal Health and Diagnostic Services at 717-772-2852, option 1.

Sick or dead wild birds should be reported to the Pennsylvania Game Commission at 610-926-3136 or

Subtypes of Avian Influenza

There are many different subtypes of influenza A viruses.  These subtypes differ and are classified based on a combination of two groups of proteins on the surface of the influenza A virus: hemagglutinin or “H” proteins, of which there are 16 (H1-H16), and neuraminidase or “N” proteins, of which there are 9 (N1-N9).  Many different combinations of “H” and “N” proteins are possible.  Each combination is considered a different subtype, and can be further broken down into different strains.  AI viruses are further classified by their pathogenicity—the ability of a particular virus strain to produce disease in domestic chickens.  Highly pathogenic avian influenza (HPAI) virus strains are extremely infectious, often fatal to domestic poultry, and can spread rapidly from flock to flock.  Low pathogenicity avian influenza (LPAI) virus strains occur naturally in wild migratory waterfowl and shorebirds, usually without causing illness.

The avian influenza viruses that cause concern in poultry and wild birds are HPAI viruses and any virus designated as H5 or H7, because H5 and H7 viruses have the capability to convert from LPAI to HPAI.  HPAI is considered a notifiable avian influenza (NAI), and when found in a country, the World Organization of Animal Health (OIE) must be alerted.


As we learn more about HPAI as it spreads across North America, PDA and its partners have developed webpages, brochures, letters, and other materials to address the needs and questions of all involved in Pennsylvania’s poultry industry.  

Other States’ HPAI Pages

Those with domesticated poultry affected by HPAI:

Pennsylvania’s Neighboring States

USDA Resources